Shocked Graham Morgan checked his inbox and found three confidential emails from payment company Allpay.net on behalf of 1066 Housing, containing spreadsheets with the personal information of up to 30,000 tenants.

Graham, 55, said: "I called 1066 because they'd made a mistake and sent me a statement telling me I was in arrears.

"At the bottom of the statement there was an advert saying I could now pay my bill in Woolworths through Allpay, and I recognised it.

"While I was on the phone I said I've had emails from Allpay. I didn't open the attachments, but I told the guy what they said, and he said, do what you want with it.

"Then a woman called me back and told me to phone Allpay. I forwarded the emails to Allpay and a woman called Claire Hughes replied and said please delete all the emails received and the files attached."

The email also stated that Allpay would be investigating why Mr Morgan was on the mailing list - which should only have contained addresses of 1066 Housing staff.

The writer, from Churchill Avenue, has deleted the emails and files. He said: "I'm glad I don't pay my rent by Allpay. There might be information in there that I wouldn't want people to know.

"1066 have 27,000 tenants. They should take more care with information like this."

1066 performance director Robin Deane said: "This is a very serious breach of confidentiality.

"We discovered this week that a tenant had received two emails in error from Allpay.net, which handle payments made through our rent cards. The tenant had registered a website domain name which is similar to 1066's, and we believe this is how the error occurred.

"The emails included names and addresses of residents who had made rent payments through Allpay.net in a two-week period in February/March, together amounts that had been paid.

"I can reassure residents that they did not include bank account details or other personal information.

"We have launched an investigation with Allpay to find out how this error occurred and they are putting additional security measures in place to prevent a similar incident happening again."

A spokesman for Allpay.net said: "We are currently working with 1066 to understand how this incident has occurred. Allpay.net takes information security extremely seriously and is subsequently conducting a full investigation."

Any 1066 tenants who have concerns are asked to call 01424 728000.